Despite significant increases in global health investment and the availability of low-cost, efficacious interventions designed to prevent mother to child HIV transmission (PMTCT) in low and middle income countries with high HIV burden, the translation of these scientific advances into effective delivery strategies has been slow, uneven and incomplete. As a result, pediatric HIV infection remains largely uncontrolled. The introduction of the Option B+ strategy ? where HIV-infected pregnant women rapidly initiate lifelong antiretroviral therapy (ART) independent of disease status ? has the potential to dramatically reduce HIV transmission during pregnancy, birth and the breastfeeding period, and as a result, it has been scaled up throughout high HIV burden countries in sub-Saharan Africa. Despite these significant investments to scale-up Option B+, results have been poor, with high rates of loss to follow-up and low viral suppression, leading to continued HIV transmission to children and HIV-associated morbidity among mothers. A previous research project (the Systems Analysis and Improvement Approach ? or SAIA ? cluster randomized trial) demonstrated that a package of systems engineering tools including cascade analysis, process mapping, and continuous quality improvement, was effective at improving flow through the PMTCT cascade across three sub-Saharan African countries. The overall goal of this application is to develop a model to deliver the SAIA intervention (SAIA-SCALE) that is led by district maternal and child health (MCH) supervisors (rather than research nurses), to serve as a foundation for national scale-up. We propose to implement the SAIA intervention in all districts in one province in Mozambique using MCH supervisors as disseminating agents, who will implement SAIA in subordinate health facilities. Using a three-year phased-in design, 12 districts will be randomly allocated into three implementation waves, and a mixed-methods evaluation will be used to assess the impact of the intervention. Our specific aims are to: Aim 1: Develop an effective district-based dissemination and implementation strategy for the SAIA intervention (SAIA-SCALE), using the RE-AIM model to evaluate the program?s Reach, Effectiveness, Adoption, Implementation, and Maintenance; and Aim 2: Using activity based micro-costing and mathematical models of HIV transmission, estimate the budget and program impact from the payer perspective to scale-up the SAIA intervention compared to the standard of care. The results of this implementation research are expected to generate knowledge of global health significance, and by providing a real-world implementation model for the SAIA intervention and programmatically relevant information, is designed to lead to rapid policy translation for future scale-up in countries with high burden of HIV and weak PMTCT delivery systems.